Rhenny Blackwater was one of the members of my family who was a zebra; genetics from Star Blackwater herself led to his birth, and he showed sheer brilliance from an early age.  He had a knack for mechanicals, and he always showed interest in such things - even into his troubled adulthood.

Rhenny (short for Renvolio) also had random seizures, as evidenced from some of the medical reports, diagrams and charts he kept, starting at about the age of seventeen summers.  He also was the only child of his parents (Lystia and Melvin Blackwater), and as such, he was a bit coddled.  So, when they were killed in a carriage collision, Rhenny took it hard.  He also became slowly convinced that he was the target of some unseen assassins.

To this end, with the entirety of the Blackwater fortune at his hooftips, he began using his knowledge to make himself more self-sufficient... and more 'safe'.

For what it was worth, Rhenny did some amazing things for the quarry: he's the one who managed to get the plumbing installed, even planning and charting each pipe and putting together the machinery needed to put it into place.  He built the high wall that surrounds the quarry to this very day.  He designed the original mining equipment that was used until Silver's hiring, and he even managed to build the magnificent gem refinery that sits on the quarry lot.

However, he was EXTREMELY paranoid, and built other things to that end.  Like a war-wagon (his words) that had a spinning blade that would potentially keep the driver safe while removing limbs from whomever might try to harm him.  He created the oil boilers that lie in wait along the quarry walls, that can heat and drop whatever substance is in them over the sides, preventing a breach by ladder.  He invented a portable cannon that could launch powerful explosives at great distances, and a smaller version that could actually be kept inside a jacket or such - the 'cannonballs' were very small, but if launched at the worst possible places, could easily kill a creature.

THIS side of Rhenny Blackwater was scary.

He locked himself up inside the quarry at one point, forbidding workers from even coming inside.  Sealing the doors and exclaiming himself to be invincible within the quarry walls he'd constructed, Rhenny stayed there for almost an entire month... but what happened to him is still a mystery to this day.

When one of the ousted workers came by to see if he had come to his senses, they found the quarry gates wide open - and Rhenny himself was nowhere to be found.  Not a hair, not a drop of blood, not even a corpse... he was just gone, as if he'd been spirited away by some unknown force.  As my ancestors didn't ALL stay at the quarry, his place was taken up by Jameson Blackwater, a nephew to Rhenny's parents, and the Blackwaters continued their legacy within the mighty walls of the Blackwater Quarry.

However, I've done a little research into things, and here's what I found:

Rhenny apparently had a strange disease that clouded his mind as he grew older; many of his medical records indicate that he might have had early-onset dementia, and that would be supported by his paranoia towards 'unknown assassins'.  He wasn't very diligent about keeping himself fed or clean towards the end of his life, and those things may have contributed to his passing.

But the fact that no body was ever recovered?

Well, it seems as if there WAS another Blackwater who'd been visiting him; Trelaney Blackwater, a pegasus mare who grew up in Appleloosa, and whose parents brought her over to play with him when they were younger.  There were a few letters from her, each asking about how things were going, how he was feeling, and all of that... but in the will leftover from Rhenny, he never mentioned her.  Not once.

Also, there are records that state she had a semi-regular carriage travelling to and from the quarry, and those dates became a bit more frequent as his paranoia climbed.  Also, there is a painting of her - by Rhenny's hoof - in the southern hall, next to the one of Horace Blackwater.  She looks... suspicious, to put it nicely.  Her muzzle is smiling, but that smile doesn't seem to reach her eyes, for some reason; maybe it was just Rhenny's way of portraying her, but it leaves a funky taste in my proverbial mouth.

In addition to this, there's also some scant evidence that Rhenny hadn't quite paid off the workers he'd tossed out; their last paychecks were never issued.  It might mean some foul play on their behalf, but I have no other evidence to support this theory.  However, if they had, say, perhaps put poor Rhenny into part of the walls, or the still-drying foundations of the refinery, it would be a fair explanation as to why his body's never turned up.  I'm scared that the day may come when the old foundations are cleared for new ones... and bones will be found among the rubble.

But Rhenny's inventions still grace the quarry today, albeit with a few changes - the war-wagon was slowly retuned to become 'Benny', and some of the pipes have been replaced over the years, the most recent replacement being Hopper #6's faulty lines after they literally blew up a while back.  But there are a few things of his creation that are interred within the Blackwater Vault, such as his small cannon and its' cannonballs, among a few other rather dastardly devices.

I hope that no one ever stumbles across them, or Equestria would get a very different view of us; we'd go from ne'er-do-wells to sinister pariahs in a hoofbeat, even if we never used any of those things against anyone.  They're just so... destructive and deadly.  I find it a wake-up call to the possibilities that a Blackwater might have, were they of a wicked enough mindset to use them.

In conclusion, Rhenny Blackwater was an individual that created much of what the quarry is today, but had a dark and sinister life that came to an abrupt and unknowable end.  Honestly, I hope he managed to find some sort of peace, and left the quarry to seek his future in the world, leaving behind the quarry for others to care for as he explored and shared his kinder inventions with everyone he met.

However, I'm more afraid that his end wasn't as kind as I hope for.  Whatever the case may be, perhaps someday the mystery will be revealed, and at least there might be something to inter within the hallowed hills of Blackwater Ridge, because I think he still deserves that.  Regardless of his latter days, the quarry wouldn't be the wonder it is without him.